Date: Fri, 11 May 2012 06:55:32

Author: Ann Reagan

Subject: Re: Refraction Lab


Semi-circular plastic dishes are as cheap as $2 each. You can find laser pointers in the same price range. Have you thought about using these tools to make one set-up for each student doing the measurement?

I suppose it might depend on the age/maturity of your students (I wouldn't want to arm a room-full of middle-schoolers with laser pointers), but this might provide one more option. Also, if you are working with your Chem department, you can use these tools to graph Index of Refraction vs. volume fraction (or mole fraction, or percent by weight etc.) of a sugar/water solution.

Date: Thu, 10 May 2012 13:38:02 -0400
From: "Anthony Lapinski"
Subject: refraction lab

Does anyone do the refraction lab where liquids are poured into plastic
semicircular dishes? You align two needles and observe their images
through the curved part of the dish.

I currently use canola oil, hydrogen peroxide, isopropyl alcohol, Karo
syrup, Sprite, vinegar, and water.

My classes have more students than liquids, so they are often waiting
around. I am looking for more variety -- some other "common" liquids which
do not pose a safety hazard (e.g., vapors).

For example, honey, mineral oil.

Does anyone use other "safe" liquids?

What about ammonia, bleach, Pine-Sol, etc? I assume the vapors might
bother some students.

I once tried acetone, but it discolored and dissolved the dish!

I realize the liquid list is limited and most of the refractive indexes
are around 1.3 - 1.5. So the observations have to be made accurately to
achieve good results.